bnxt_en: Fix counter overflow logic.
authorMichael Chan <michael.chan@broadcom.com>
Mon, 16 Nov 2020 00:27:51 +0000 (19:27 -0500)
committerJakub Kicinski <kuba@kernel.org>
Tue, 17 Nov 2020 01:39:46 +0000 (17:39 -0800)
commitfa97f303fa4cf8469fd3d1ef29da69c0a3f6ddc8
tree79174f84cf82e8fe05968ff986067ccc189b19a1
parenteba93de6d31c1734dee59909020a162de612e41e
bnxt_en: Fix counter overflow logic.

bnxt_add_one_ctr() adds a hardware counter to a software counter and
adjusts for the hardware counter wraparound against the mask.  The logic
assumes that the hardware counter is always smaller than or equal to
the mask.

This assumption is mostly correct.  But in some cases if the firmware
is older and does not provide the accurate mask, the driver can use
a mask that is smaller than the actual hardware mask.  This can cause
some extra carry bits to be added to the software counter, resulting in
counters that far exceed the actual value.  Fix it by masking the
hardware counter with the mask passed into bnxt_add_one_ctr().

Fixes: fea6b3335527 ("bnxt_en: Accumulate all counters.")
Reviewed-by: Vasundhara Volam <vasundhara-v.volam@broadcom.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
drivers/net/ethernet/broadcom/bnxt/bnxt.c